Synergistic Molecular Modification of NiO_x for High-Performance Inverted Perovskite Solar Cells

Nickel oxide (NiO_x) serves as the preferred hole transporting layer (HTL) for inverted perovskite solar cells (PSCs) due to its good chemical stability and facile solution processability. However, the uncompetitive device performance of PSCs using the pristine NiO_x layer has been limited by its intrinsic defect stacking and poor interface contact. Herein, we propose a cooperative interfacial modification strategy to tailor the electronic properties of NiO_x by introducing the self-assembled molecule (SAM) interlayer with PABr modification. The SAM molecule can effectively passivate the oxygen vacancies on the surface and regulate the energy level of NiO_x by forming an interfacial dipole. In addition, the PABr molecule can further optimize the molecular arrangement of the SAMs and modify the surface wetting of HTLs. The high-quality perovskite film with improved grain sizes and reduced defect density was achieved on the modified NiO_x layer, facilitating enhanced charge transport and significantly alleviated nonradiative recombination loss within devices. Consequently, the target device achieved an improved efficiency of 25.13%, outperforming 23.28% of the NiO_x. In addition, the 107.0 cm² flexible solar modules achieve an impressive efficiency of 16.24%, illustrating the feasibility of the proposed molecular modification for scalable fabrication. Our work underscores the importance of interfacial tailoring on the buried interface to boost the efficiency and stability of PSCs.